自动编排接口现在立即返回 202 + jobId，不会再等待 15 秒导致 Axios 超时。

任务参数、状态和结果持久化到 MySQL。
接入现有 outbox；配置 BackgroundJobs__Transport=RabbitMq 时使用 RabbitMQ 队列 exam.arrangement，否则使用 InMemory worker。
服务重启后可恢复未完成任务。
前端显示排队/执行/完成/失败状态，刷新页面可恢复正在执行的任务。
编排期间禁止修改、删除或发布对应计划。
补考原有“一键生成”保留，并与编排任务互斥。
运维后台增加“考试与补考编排”失败任务筛选。

src/Jiaowu.Api/Domain/Academic/ExamEntities.cs

@@ -14,6 +14,40 @@ public sealed class ExamPlan : EntityBase
     public ICollection<ExamRoomAssignment> Rooms { get; set; } = [];
 }
 
+public sealed class ExamArrangementJob : EntityBase
+{
+    public ExamArrangementKind Kind { get; set; }
+    public Guid PlanId { get; set; }
+    public Guid? ActivePlanId { get; set; }
+    public Guid? RequestedByUserId { get; set; }
+    public string? SessionIdsJson { get; set; }
+    public bool AssignClassrooms { get; set; }
+    public bool AssignInvigilators { get; set; }
+    public ExamArrangementJobStatus Status { get; set; } =
+        ExamArrangementJobStatus.Queued;
+    public int TotalSessions { get; set; }
+    public int ProcessedSessions { get; set; }
+    public string? CurrentStep { get; set; }
+    public string? ResultMessage { get; set; }
+    public string? ErrorMessage { get; set; }
+    public DateTime? StartedAt { get; set; }
+    public DateTime? CompletedAt { get; set; }
+}
+
+public enum ExamArrangementKind
+{
+    FormalExam = 1,
+    MakeupExam = 2
+}
+
+public enum ExamArrangementJobStatus
+{
+    Queued = 1,
+    Running = 2,
+    Succeeded = 3,
+    Failed = 4
+}
+
 public sealed class ExamSession : EntityBase
 {
     public Guid ExamPlanId { get; set; }

src/Jiaowu.Api/Domain/System/BackgroundJobOutboxMessage.cs

@@ -30,7 +30,8 @@ public enum BackgroundJobKind
 {
     AutomaticSchedule = 1,
     SchedulePublish = 2,
-    MakeupExamAuto = 3
+    MakeupExamAuto = 3,
+    ExamArrangement = 4
 }
 
 public enum BackgroundJobOutboxState